Brief Summary of Minutes of Annual Meeting

III. Principal Accomplishments by Objective: Objective 1: To identify and characterize plant microbe interactions that provide suppression of diseases caused by soilborne pathogens. California (UCR - Stanghellini) identified an entomopathogenic fungus (Beauveria bassiana) which rapidly kills shore flies and developed a novel method for the delivery of the entomopathogen in greenhouse cultivation systems. A chemical that selectively enhances the population of fluorescent pseudomonads in recycled irrigation water was identified. Enhancement of the population was correlated to control of root rot of diverse plants caused by species of Pythium and Phytophthora. California (UCR - Becker): Strains of D. oviparasitica, F. oxysporum and Zoogloea sp. have been identified as potentially involved in soil suppressiveness against H. schachtii, the beet cyst nematode. Re-introduction of D. oviparasitica transferred and established the suppressiveness to a similar degree as in the original suppressive soil. Three additional beet cyst nematode-suppressive soils were identified in a field survey of H. schachtii-infested sites. The identification of the causal factors in the soil suppressiveness at the UC Riverside field station will provide the basis for studies that address the introduction and management of suppressive factors in disturbed and non-disturbed environments. The survey indicated that suppressive soils could be found in commercial agricultural fields. However, their occurrence is rare and not obviously related to physical soil properties. California (UCR - Borneman) demonstrated the effectiveness of D. oviparasitica in controlling H. schachtii populations in both different soil types and field trials. These results bode well for the future development of new and more sustainable H. schachtii management strategies. California (UCR - Menge): Further progress has been made in isolating and identifying biocontrol agents of P. cinnamomi. The molecular identification of the microorganisms in the suppressive Somis soil, which is the culmination of four years worth of work, has begun and should be done in six months. Pseudomonas constantinii and P. tolaasii have been identified from New Guinea soil as excellent biocontrol agents of P. cinnamomii. Further evaluation of these organisms will begin pending receipt of USDA permits. Greenhouse evaluation of other potential biocontrol agents, including from commercial sources, has been unsuccessful but is ongoing. New York (Abawi): In collaboration with the soil health program team at Cornell, the root health status (general soil suppressive capacity) of soils collected from a large number of vegetable production sites statewide was determined by conducting a soil bioassay with beans. Results obtained demonstrated that significant differences in root health occur among these soils. Oregon (Parke): Phytophthora ramorum causes Sudden Oak Death and ramorum blight on many nursery crops. This quarantine pathogen is considered to be a strictly foliar pathogen. We discovered that P. ramorum in potting media can infect rhododendron roots, leading to disease of stems and leaves via vascular tissue. Current plant inspections and nursery certification are based solely on foliar samples. Recovery of P. ramorum from symptomless root tissue demonstrates the need to monitor belowground sources of inoculum. This may be necessary to limit transmission of P. ramorum from nursery plants to susceptible oaks and other native vegetation in the eastern U.S. Future work will address how P. ramorum survives in potting media and recirculating irrigation water and will determine if these will be amenable to biological control approaches. Washington (Paulitz): Rhizoctonia bare patch is caused by R. solani AG-8, and is a major problem in direct-seeded wheat and barley. Because of the wide host range of this pathogen, crop rotation had not been considered feasible as a cultural practice to manage this disease. Recent field trials have demonstrated that wheat following barley has less disease and greater yield than continuous wheat. Because barley is also a susceptible host, the rotation effect is not due to lack of a host, but may be due to a shift in microbial communities. This suppression has also been demonstrated in the greenhouse, with intact soil cores taken from the centers of the patches and planted with 5 cycles of barley over one year. At the start of the experiment, barley was stunted, but by the end of the experiment, the stunting was not visible in most patches. The pathogen was still present in the cores that had become suppressive. This suggests microbial suppression may be involved. Objective 2: To understand how biological and environmental factors regulate microbial populations and the expression of genes responsible for disease suppression. Alaska (McBeath): Trichoderma atroviride is a cold tolerant fungus that parasitizes a wide range of plant pathogenic fungi. T. atroviride is very robust. Results of compatibility studies show that T. atroviride growth is not adversely affected by high concentrations of heavy metals. T. atroviride was found efficacious against Armillaria root rot on fruit trees. No further dieback was found on trees treated with T. atroviride. Treated trees are significantly taller with thicker trunks, larger and greener leaves than the untreated control. b-N-acetyl-D-glucosaminidase, b-1,6-glucanases and endo-b-1,3-glucanase are important enzymes involved in biocontrol by T. atroviride. The 73 kDa b-N-acetyl-D-glucosaminidase was produced only when T. atroviride was grown with S. sclerotiorum. T. atroviride produced the 93 kDa b-N-acetyl-D-glucosaminidase when it was grown with other plant pathogenic fungi. b-1,6-glucanases produced by cold tolerant T. atroviride were influenced by carbon source and pH. The 77 kDa endo-b-1,3-glucanase showed strong antifungal activity by inhibiting spore germination of Botrytis cinerea. Glutathione S-transferases (GSTs) and late blight resistance (R1) genes were shown to be responsive to biotic and abiotic stresses. Among the 33 potato cultivars tested, 3 cultivars had an amplification product for R1, 3 had amplification products for R1 and GST and 3 cultivars had amplification products for R1 and GST which are linked. Arizona (Pierson): Characterization of the molecular mechanisms responsible for phenazine gene regulation in P. aureofaciens 30-84 is continuing to provide insights into how root-associated bacteria sense its environment and response to it by altering patterns of gene expression. Ecological approaches are being used to quantify the role of cross-communication among rhizobacteria on phenazine gene expression in situ. Oregon (Loper): The genomic sequence of Pseudomonas fluorescens Pf-5 was completed in 2003 at TIGR and manual annotation is nearly complete (http://www.ars-grin.gov/hcrl/Pf5genome/index.htm). The total lengths of known and putative gene clusters encoding for antibiotic or siderophore biosynthesis is estimated at ca. 400 kb, representing approximately 5.7% of the 7.1 Mb genome of Pf-5. Of the 6147 putative genes in the Pf-5 genome, 681 have no homologs in the genomes of other Pseudomonas whose genome sequences are known. Oligomers (70 mers) representing each gene in the Pf-5 genome were designed for high-density microarrays. Low-density oligonucleotide microarrays were used to evaluate the influence of PltR (a regulator of the pyoluteorin biosynthesis gene cluster) on expression of 81 genes by Pf-5 and results were confirmed with quantitative RT-PCR. The same methods will be employed in 2005 to evaluate patterns of gene expression using the high-density (18K feature) microarray of Pf-5. Oregon (Parke): Sequencing the genome of biological control strain Burkholderia cepacia AMMD will enable investigations of the molecular basis of biocontrol and the soil factors which affect gene expression. Washington (Paulitz) has developed species-specific primers for the molecular detection of 10 Pythium spp., 3 groups of Rhizoctonia oryzae, and 3 groups of R. solani. These methods will allow the quantification of these pathogens from plant and soil samples, and the study of pathogen ecology and the influence of biological control agents. Objective 3: To develop and implement economic biological control systems to achieve sustainable agriculture. New York (Abawi): The plant activators Actigard and BioYield were evaluated in experimental fields for their efficacy against R. solani and Meloidogyne hapla on table beets and onions, respectively. Both products reduced the severity of diseases caused by the target pathogens and increased yield as compared to the untreated checks. The efficacy of these and other products against soilborne pathogens of vegetable crops will be re-evaluated in 2005. Montana (Callan): Peppermint stolon decay is caused by a complex of soilborne pathogens, including Pythium, Rhizoctonia, Fusarium, and Sclerotinia. Replicated plots were established to evaluate several biocontrol fungi and bacteria for protection of peppermint and improve winter survival. Establishment of a vigorous peppermint stand, free of diseases, insects, and weeds, is essential to the success and profitability of the peppermint industry in Montana. IV. Work Planned for Next Year: The members of this project plan to continue and advance the research efforts currently in progress. Several states, including CA and NY, will continue evaluating soils for potential suppressiveness and will determine the causal agents and mechanisms. WA, AZ, OR, and AK will continue to elucidate genetic mechanisms involved in biocontrol. California will also conduct factorial trials with strains of D. oviparasitica, F. oxysporum and Zoogloea sp. to evaluate potential interactions in reducing the beet cyst nematode population. Pseudomonas constantinii and P. tolaasii will be tested for control of P. cinnamomi. Application of biocontrol technology will be studied in several states. Plant activators, available biological control preparations and other products will be evaluated against soilborne pathogens and their damage to crops in NY and MT. Oregon will determine how soil and potting media components affect the survival of P. ramorum, and begin investigations on the survival and biological control of this pathogen in recirculating irrigation water used in many nurseries. They will also determine if colonization of roots and vascular tissue occur in other susceptible host species. V. Collaboration with Other W-147 Members: The W-1147 committee members have traditionally been active in research collaboration. Mike Stanghellini (CA-UCR) obtained two Pseudomonas isolates from L. S. Pierson (AZ) for investigations relating to N-Serve- amended nutrient solutions and initiated collaborative studies with James Borneman on the identification of microbes that induce germination of ascospores of M. cannonballus. Ole Becker (CA-UCR) and John Menge (CA-UCR) are also collaborating with James Borneman and his lab. Jenifer McBeath (AK) has provided Trichoderma atroviride to Nancy Callan (MT) for peppermint stolon decay studies. Jennifer Parke (OR) will confer and collaborate with John Menge (CA-UCR) and Mike Stanghellini (CA-UCR) on approaches for biocontrol of Phytophthora species in potting media and recirculating irrigation water used in nursery crop production. Tim Paulitz (WA) has collaborated with Nik Grunwald (WA), looking at ecology of Pythium in native soils and has also discussed ideas about Phytophthora suppression and parallels with Rhizoctonia patch suppression with John Menge (CA-UCR) and his graduate students. The WA unit has a long collaboration with L. S. Pierson (AZ) in studying phenazine biosynthetic pathways.

ALASKA Cheng, M., Gay, P. A, and McBeath, J. H. 2004. Enzyme profiles associated with a cold tolerant Trichoderma atroviride during low temperature biocontrol of pathogenic fungi. Phytopathology 94:S18. Cheng, M., Gay, P. A. and McBeath, J. H. 2004. Trichoderma atroviride strain biotype 603, ATCC 74018 73 kDa N-acetyl-D-glucosaminidase gene, partial cds. GenBank Accession Number: AY646221, National Center for Biotechnology Information, Bethesda, MD. Cheng, M., Gay, P. A. and McBeath, J. H. 2004. Trichoderma atroviride strain biotype 453, ATCC 74016 73 kDa N-acetyl-D-glucosaminidase gene, partial cds. GenBank Accession Number: AY612745, National Center for Biotechnology Information, Bethesda, MD. Cheng, M., Gay, P. A. and McBeath, J. H. 2004. Trichoderma atroviride strain biotype 861, ATCC 74015 73 kDa N-acetyl-D-glucosaminidase gene, partial cds. GenBank Accession Number: AY646222, National Center for Biotechnology Information, Bethesda, MD. Gay, P. A. and McBeath, J.H. 2004. Solanum tuberosum cultivar German Butterball late blight resistance gene, partial sequence. GenBank Accession Number: AY582921, National Center for Biotechnology Information, Bethesda, MS. McBeath, J. H., Cheng, M., Gay, P., Ma, M., and Alden, J. 2004. First report of Leptographium abietinum associated with blue stain on declining western Siberian larch in Alaska. Online. Plant Health Progress doi: 10. 1094/PHP-2004-0326-01-HN. Gay, P. A. and McBeath, J.H. 2004. Solanum tuberosum cultivar 24-3 late blight resistance gene, partial sequence. GenBank Accession Number: AY582922, National Center for Biotechnology Information, Bethesda, MS. Gay, P. A. and McBeath, J.H. 2004. Solanum tuberosum cultivar Yellow Finn late blight resistance gene, partial sequence. GenBank Accession Number: AY582923, National Center for Biotechnology Information, Bethesda, MS. Gay, P. A. and McBeath, J.H. 2004. Solanum tuberosum cultivar Reba glutathione S-transferase cold induced gene, partial sequence. GenBank Accession Number: AY582924, National Center for Biotechnology Information, Bethesda, MS. Gay, P. A. and McBeath, J.H. 2004. Solanum tuberosum cultivar 772 late blight resistance gene, partial sequence. GenBank Accession Number: AY582925, National Center for Biotechnology Information, Bethesda, MS. Gay, P. A. and McBeath, J.H. 2004. Solanum tuberosum cultivar Snow Chip late blight resistance and cold induced glutathione S-transferase genes, partial sequence. GenBank Accession Number: AY582926, National Center for Biotechnology Information, Bethesda, MS. Gay, P. A. and McBeath, J.H. 2004. Solanum tuberosum cultivar Iditared late blight resistance gene, partial sequence. GenBank Accession Number: AY582927, National Center for Biotechnology Information, Bethesda, MS. Gay, P.A., McBeath, J.H. and Yokogi, T. 2004. Urocystis agropyri large subunit ribosonal RNA gene, partial sequence. GenBank Accession Number: AY547283, National Center for Biotechnology Information, Bethesda, MS. ARIZONA Morello, JE, Pierson, EA, and LS Pierson III. 2004. Negative cross-communication among wheat rhizosphere bacteria: Effect on antibiotic production by the biological control bacterium Pseudomonas aureofaciens 30-84. Appl. Environ. Microbiol. 70:3103-3109. McLean RJ, Pierson LS III, Fuqua C. 2004. A simple screening protocol for the identification of quorum signal antagonists. J Microbiol Methods. 58:351-360. Wijeratne EM, Carbonezi CA, Takahashi JA, Seliga CJ, Turbyville TJ, Pierson EE, Pierson LS III, VanEtten HD, Whitesell L, Bolzani Vda S, Gunatilaka AA. 2004. Isolation, optimization of production and structure-activity relationship studies of monocillin I, the cytotoxic constituent of Paraphaeosphaeria quadriseptata. Antibiot (Tokyo).57:541-546. Zhan J, Wijeratne EM, Seliga CJ, Zhang J, Pierson EE, Pierson LS III, Vanetten HD, Gunatilaka AA. 2004. A new anthraquinone and cytotoxic curvularins of a Penicillium sp. from the rhizosphere of Fallugia paradoxa of the Sonoran desert. J Antibiot (Tokyo). 57:341-344. He, J, Wijeratne, EMK, Bashyal, BP, Zhan, J, Seliga, CJ, Liu, MX, Pierson, EA, Pierson, LS III, VanEtten, HD, Ginatilaka, AAL. 2004. Cytotoxic and other metabolites of Aspergillus inhabiting the rhizosphere of Sonoran Desert plants. J. Nat. Prod. (in press). CALIFORNIA Becker, J.O., and J. Borneman 2004. Decoding the nature of a nematode-suppressive soil. Phytopathology 94:S129 (Abstr.). Becker, J.O, and J. Borneman 2004. Analysis of biological nematode population control: a case study. California Conference on Biological Control IV (Ed. M.S. Hoddle), Berkeley, CA, 23-27. Borneman, J., R. Olatinwo, B. Yin, and J.O. Becker 2004. An experimental approach for identifying microorganisms involved in specified functions: utilization for understanding a nematode suppressive soil. Australasian Plant Pathology 33:151-155. Chen, X., and J.O. Becker 2004. Dactylella oviparasitica as biocontrol agent for Meloidogyne incognita in tomato. Proceedings 15th International Plant Protection Congress, Beijing, China May 11-16,2004, p. 158 (Abstr.). El-Hamalawi, Z.A., and Stanghellini, M.E. 2004. Disease development on lisianthus (Eustoma grandiflorum) following aerial transmission of Fusarium avenaceum by adult shore flies, fungus gnats, and moth flies. Phytopathology 94:S27. McDonald, V.T. and J.A. Menge. 2004. Microbial suppression of Phytophthora cinnamomi in avocado soils. Phytopathology 94:S68 (Abstr.). Menge, J.A. and McDonald, V.T. 2004. Management of soil microorganisms for the control of Phytophthora root rot. Phytopathology 94:S125 (Abstr.). Olatinwo, R.O., B. Yin, J.O. Becker, and J. Borneman. 2004. An approach for identifying microorganisms involved in soil suppressiveness: utilization for identifying microorganisms that suppress the plant-parasitic nematode, Heterodera schachtii. Phytopathology 94:S78 (Abstr.). Pagliaccia, D., Merhaut, D., and Stanghellini, M.E. 2004. Enhancement of the fluorescent pseudomonad population after amending the recirculating nutrient solution of hydroponically-grown plants with a nitrogen stabilizer. Phytopathology 94:S80. Radewald,K.C., Ferrin, D.M., and Stanghellini, M.E. 2004. Sanitation practices that inhibit reproduction of Monosporascus cannonballus in melon roots left in the field after crop termination. Plant Pathology 53:660-668. Stanghellini, M.E., Waugh, M.M., Radewald, K.C., Kim, D.H., Ferrin, D.M. and Turini, T. 2004. Crop residue destruction strategies that enhance rather than inhibit reproduction of Monosporascus cannonballus. Plant Pathology 53:50-53. Stanghellini, M.E., Kim, D.H., Waugh, M.M., Ferrin, D.M., Alcantara, T. and Rasmussen, S.L. 2004. Infection and colonization of melon roots by Monosporascus cannonballus in two cropping seasons in Arizona and California. Plant Pathology 53:54-57. Stanghellini, M.E., and El-Hamalawi, Z.A. 2004. Efficacy of Beauveria bassiana on colonized millet seed as a biopesticide for the control of shore flies in greenhouses. Phytopathology 94:S98. Yin, B.A., A.J. Scupham, J.A. Menge, and J. Borneman. 2004. Identifying microorganisms similar to that of the pathogen: a new investigative approach for discovering biocontrol organisms. Plant and Soil 259:19-27. MONTANA Yang, Y., Chang, K. F., Hwang, S. F., Callan, N. W., Howard, R. J., and Blade, S. F. 2004. Biological control of Pythium damping-off in Echinacea angustifolia with Trichoderma species. Zeitschrift fur Pflanzenkrankheiten and Pflanzenschutz 111:126-136. NEW YORK Abawi, G. S., J. W. Ludwig, and C. H. Petzoldt. 2004. Assessing root health by a soil bioassay with beans as an indicator of soil health. Phytopathology 94 (Suppl.): S1 (Abstr. #579B). Abawi, G. S. 2004. Soil; Health Program Work Team at Cornell. PP. 35-36. Proceedings III, Empire State Fruit & Vegetable Expo, CCE, Cornell University, Ithaca, NY. Abawi, G. S. and J. W. Ludwig. 2004. Beet diseases, management options and research results, 2003. PP. 106-108. Proceedings III, Empire State Fruit & Vegetable Expo, CCE, Cornell University, Ithaca, NY. OREGON Anderson, L.M., Stockwell, V.O., and Loper, J.E. 2004. An extracellular protease of Pseudomonas fluorescens Pf-5 inactivates antibiotics of Pantoea agglomerans. Phytopathology 94:1228-1234. Brodhagen, M., Henkels, M. D., and Loper, J. E. 2004. Positive autoregulation of the antibiotic pyoluteorin in the biological control organism Pseudomonas fluorescens Pf-5. Appl. Environ. Microbiol. 70:1758-1766. Hansen, E. M., Parke, J. L., and Sutton, W. 2004. Susceptibility of Oregon forest trees and shrubs to Phytophthora ramorum: a comparison of artificial inoculation and natural infection. Plant Dis. (in press). Lewis, C. D., Roth, M. L., Choquette, C. J. and Parke, J.L. 2004. Root infection of rhododendron by Phytophthora ramorum. Phytopathology 94:S60 (Abstr.) Parke, J., Frankel, S., Alexander, J. and Thomas, C. 2004. Phytophthora ramorum Educate to Detect (PRED) Program. http://www.ncipmc.org/sod/ Parke, J. L., Linderman, R. G., Osterbauer, N. K., and Griesbach, J. A. 2004. Detection of Phytophthora ramorum blight in Oregon nurseries and completion of Kochs Postulates on Pieris, Rhododendron, Viburnum, and Camellia. Plant Dis. 88:87. Parke, J., Pscheidt, J., and Linderman, R. 2004. Phytophthora ramorum: a guide for Washington nurseries. 8 pp. Washington State Nursery and Landscape Association. Parke, J. L. and Roth, M. L. 2004. Relative virulence of Phytophthora ramorum isolates in Oregon. Phytopathology 94:S81 (Abstr.). Parke, J. L., Roth, M. L., Lewis, C. and Choquette, C.J. 2004. Infection of Rhododendron macrophyllum roots, stems, and leaves by soilborne inoculum of Phytophthora ramorum. Proceedings, IUFRO Conference on Phytophthora in Forests, Freising, Germany, Sept. 11-17. Temple, T., Stockwell, V.O., Loper, J.E., and Johnson, K.B. 2004. Bioavailability of iron to Pseudomonas fluorescens strain A506 on flowers of pear and apple. Phytopathology 94:1286-1294. WASHINGTON Ahuja, E. G., Mavrodi, D. V, Thomashow, L. S., and Blankenfeldt, W. 2004. Overexpression, purification and crystallization of PhzA, the first enzyme of the phenazine biosynthesis pathway of Pseudomonas fluorescens 2-79. Acta Crystallogr. D 60:1129-1131. Allende-Molar, R., Landa, B. B., and Weller, D. M. 2004. Long-term survival of different genotypes of 2,4-diacetylphloroglucinol (DAPG)-producing Pseudomonas fluorescens in soil. Phytopathology 94:S4 (Abstr.). Blankenfeldt, W., Kuzin, A., Skarina, T., Korniyenko, Y., Tong, L., Bayer, P., Janning, P., Thomashow, L. S., and Mavrodi, D. V. 2004. Structure and function of the phenazine biosynthetic protein PhzF from Psesudomonas fluorescens. Proc. Natl. Acad. Sci. USA 101:16431-16436. Blouin Bankhead, S., Brown, A., Son, M. Y., Thomashow, L. S., and Weller, D. M. 2004. Population dynamics and non-target effects of transgenic Pseudomonas fluorescens in the rhizosphere of wheat and pea. Phytopathology 94:S8 (Abstr.). Blouin-Bankhead, S., Landa, B., Lutton, E., Weller, D. M., and McSpadden Gardener, B. B. 2004. Minimal changes in rhizobacterial population structure following root colonization by wild type and transgenic biocontrol strains. FEMS Microbiology Ecol. 49:307-318. De La Fuente, L., Landa, B. B., Thomashow, L. S., and Weller, D. M. 2004. Dynamics of rhizosphere competition among genotypes of 2,4-diacetylphlorogucinol (DAPG)-producing Pseudomonas fluorescens depends on the host crop. Phytopathology 94:S24 (Abstr.). De La Fuente, L., Thomashow, L. S., Weller, D. M., Bajsa, N., Quagliotto, L., Chernin L., and Arias, A. 2004. Pseudomonas fluorescens UP61 isolated from birdsfoot trefoil rhizosphere produces multiple antibiotics and exerts a broad spectrum of biocontrol activity. Eur. J. Plant Pathol. (in press). Higginbotham, R. W., Paulitz, T. C., and Kidwell, K. K. 2004. Virulence of Pythium species isolated from wheat fields in eastern Washington. Plant Dis. 88:1021-1026. Higginbotham, R. W., Paulitz, T. C., Campbell, K. G. and Kidwell, K. K. 2004. Evaluation of adapted wheat cultivars for tolerance to Pythium root rot. Plant Dis. 88:1027-1032. Huang, Z., Bonsall, R. F., Mavrodi, D. V., Weller, D. M., and Thomashow, L. S. 2004. Transformation of Pseudomonas fluorescens with genes for biosynthesis of phenazine-1-carboxylic acid improves biocontrol of Rhizoctonia root rot and in situ antibiotic production. FEMS Microbiol. Ecol. 49:243-251. Mavrodi, D. V., Bleimling, N., Thomashow, L. S., and Blankenfeldt, W. 2004. The purification, crystallization and preliminary structural characterization of PhzF, a key enzyme in the phenazine-biosynthesis pathway from Pseudomonas fluorescens 2-79. Acta Crystallogr. D 60:184-186. Mavrodi, D., Validov, S., Mavrodi, O., De La Fuente, L., Boronin, A., Weller, D., and Thomashow, L. 2004. Bacteriocin activity among 2,4-diacetylphloroglucinol (DAPG)-producing fluorescent Pseudomonas spp. Phytopathology 94:S67 (Abstr.). Mavrodi, O. V., Mavrodi, D. V., Weller, D. M., and Thomashow L. S. 2004. Role of sss recombinase and dsbA in root colonization by Pseudomonas fluorescens Q8r1-96. Phytopathology 94:S67 (Abstr.). Okubara, P., and Paulitz, T. C. 2004. Simultaneous identification and quantification of Rhizoctonia solani and R. oryzae from root samples using real-time PCR. Phytopathology 94:S77 (Abstr.). Okubara, P.A., and Skinner, D.Z. 2004. Microarray expression profiles of wheat roots and shoots during cold stress and root colonization by Pseudomonas fluorescens. Plant Biology 2004, Abstract No. 694 (Abstr.). Okubara, P.A., Kornoely, J.P., and Landa, B.B. 2004. Rhizosphere colonization of hexaploid wheat by Pseudomonas fluorescens strains Q8r1-96 and Q2-87 is cultivar-variable and associated with changes in gross root morphology. Biological Control, vol. 30, p. 392-403. Paulitz, T. C. and Rossi, R. E. 2004. Spatial distribution of Rhizoctonia solani and Rhizoctonia oryzae at three different scales in direct-seeded wheat. Can. J. Plant Path. 26:419 (Abstr.). Paulitz, T. C. And Schroeder, K. L. 2004. A method for the quantification of Rhizoctonia solani and Rhizoctonia oryzae from soil using toothpicks. Phytopathology 94:S82 (Abstr.). Paulitz, T. C., Dugan, F., Chen, W., and Grünwald, N. J. 2004. First report of Pythium irregulare on lentils in the United States. Plant Disease 88:310. Schroeder, K. L. and Paulitz, T. C. 2004. Real-time PCR identification of Pythium spp. from cereals in eastern Washington. Phytopathology 94:S94 (Abstr.). Thomashow, L. S., Delaney, S. M., Mavrodi, D. V., and Weller, D. M. 2004. Sequences encoding phzO and methods. United States Patent No. 6,737,260 B1 (Patent). Validov, S., Mavrodi, O., De La Fuente, L., Boronin, A., Weller, D., Thomashow, L., and Mavrodi, D. 2004. Antagonistic activity among 2,4-diacetylphloroglucinol-producing fluorescent Pseudomonas spp. FEMS Microbiol. Lett. (in press). Weller, D. M., van Pelt, J. A., Mavrodi, D. V., Pieterse, C. M. J., Bakker, P. A. H. M., and van Loon, L. C. 2004. Induced systemic resistance (ISR) in Arabidopsis against Pseudomonas syringae pv. tomato by 2,4-diacetylphloroglucinol (DAPG)-producing Pseudomonas fluorescens. Phytopathology 94:S108 (Abstr.).